As integrated devices continue to scale to smaller dimensions, the ability to pattern features becomes increasingly difficult. These difficulties include in one aspect the ability to etch features to preserve or transfer a pattern into a substrate. In many device applications a patterned feature may include a metal layer that is difficult to etch because the metal does not readily form volatile etch products using known reactive ion etching or similar processes. Etching of metal layers via physical sputtering may be problematic because of the tendency for sputtered species of a given metal layer to redeposit on unwanted surfaces of the substrate including on surfaces of device features being formed. This may lead to patterned structures such as pillars or lines having non-vertical sidewalls, as well as having excessive material redeposited from etching of a non-volatile metal underlayer.
With respect to these and other considerations the present improvements may be useful.